During an operation in the abdominal region, it is often necessary to strengthen the abdominal wall using an inserted areal implant. It is known to use nets made from the non-resorbable plastics polypropylene or polyester or from the slowly resorbable polyglactin 910 (a copolymer of glycolide and lactide in the ratio 9:1) for such implants. Metallic implants are also used.
The known implant nets have some disadvantages. For example, they are relatively heavy, i.e. the areal weight is as a rule more than 50 g/m.sup.2 and predominantly even ca. 100 g/m.sup.2. If the implants are not resorbable, a relatively large quantity of foreign substance thus remains permanently in the body. In terms of tearing strength, the known implant nets are frequently over-sized, i.e. they have a much higher strength than is required from a physiological viewpoint. These properties, combined with the usual, net-like construction of the basic structure of the previously known implants, can mean that the well-being and the mobility of a patient who is fitted with such an implant are limited.
Another disadvantage of the previously known areal implants is that, although they conform better to the abdominal wall after the operation if they are more flexible, they can then only be inserted with difficulty, since e.g. they fold readily. On the other hand, although a rigid implant is easy to handle, it can lead to problems in the long term after insertion into the abdominal wall, as already mentioned. The previously known areal implants are thus either too flexible for ease of working during an operation or too rigid for an unproblematical interaction with the abdominal wall into which they are inserted.